There are commercially available LKS (Lane Keep Support Systems) and other operation support devices for maintaining in-lane running of a vehicle.
For the operation support devices, the support information for running in the lane is provided to the driver by the steering reaction force or other means corresponding to the lateral position in the lane where the vehicle runs.
For example, according to the technology described in Japanese Kokai Patent Application No. 2005-219719, changing of the seat shape notifies the driver of the vehicle's angle and lateral position in the lane of travel.